Push-in type of light socket



March 31, 1970 J. w. PETERSON ET AL 3,504,

PUSH-IN TYPE OF LIGHT SOCKET Filed June 19, 1967 United States Patent 3,504,329 PUSH-IN TYPE OF LIGHT SOCKET John W. Peterson, Douglaston, and Henry Schick,

Commack, N.Y., assignors to Gilbert Manufacturing Co., Inc., Long Island City, N.Y., a corporation of New York Filed June 19, 1967, Ser. No. 647,005 Int. Cl. H01r 25/00, 25/10, 13/54 US. Cl. 339-73 17 Claims ABSTRACT OF TIE DISCLOSURE In any application where an electric lamp, or plurality of lamps are used, a like number of lamp sockets must be provided. One typical multiple lamp application is in Christmas tree lighting sets wherein a number of lamp sockets are fastened to a two-lead electrical conductor and a respective electric light bulb is held by each socket. In the usual case, the light sockets are of a molded plastic type and are provided with screw threads on the interior of their walls to receive and engage the screw threads of the light bulb to hold it in the socket.

While the screw threads on the walls of the socket perform their intended function, they give rise to several disadvantages. First of all, it is somewhat difiicult to accurately mold these threads on the socket interior walls using conventional injection molding processes. During the molding operation the mold has a tendency to strip the threads as the mold is removed. Further, as the mold wears, the thread walls become less well defined. Both of these, and other molding problems give-rise to a large number of rejects during socket manufacture and, consequently, raises the cost of producing such sockets. Another disadvantage arises during assembly of lighting sets in which a number of such sockets and lamps are used. Here the lamp bulbs are manually screwed into the sockets one by one. This procedure requires a considerable amount of time for an operator to insert a single bulb into each socket and screw it down tight into electrical contacting engagement with the sockets electrical contacts. This also raises the cost of the lighting sets.

Heretofore, several arrangements have been proposed for eliminating the molding of screw threads on the interior wall of an electric lamp socket. Several of these arrangements comprise, for example, forming one of the bulb engaging electrical contact members with a number of steps to serve as the threaded socket member rather than molding the threads on the wall. Other socket arrangements include the use of spring-type contact members or auxiliary spring holding members, into which a light bulb is pressed and held. While all of these prior art socket arrangements have some utility, they have also been found to have disadvantages and several are somewhat costly to produce.

In the present invention, a novel and simplified molded light socket is provided which permits a screw-type light bulb to be pushed directly into the socket and be held rather than having to be screwed therein. In accordance with the invention, a light socket is molded of plastic material and is formed with a resilient or semi-resilient bulb holding member therein. In the preferred embodiment of the invention, the holding member includes one or more ribs formed on the socket interior wall which expand or deform to grasp and hold the light bulb base as it is pushed into the socket.

The present invention permits sockets to be made less expensively, since the absence of screw threads gives rise to fewer rejects. In addition, it permits an operator assembling lighting sets to push the screw-threaded bulbs directly into the socket rather than screwing them in. This results in a substantial saving of labor and costs related thereto.

It is therefore an object of the present invention to provide a light socket for screw-type electric lamps in which the lamp can be pushed directly into the light socket rather than being screwed in.

A further object is to provide a socket for electric lamps formed with one or more resilient or semi-resilient members for holding a screw-type electric lamp.

Another object is to provide a molded plastic lamp socket formed with integral holding members which engage and hold a screw-type lamp pushed directly therein.

Other objects and advantages of the present invention will become more apparent upon reference to the following specification and the annexed drawings, in which:

FIG. 1 is a top plan view of a socket made in accordance with the present invention;

FIG. 2 is an elevational view taken in cross-section taken along lines 22 of FIG. 1;

FIG. 3 is an elevational view of the socket of FIG. 1, taken in cross-section turned from FIG. 2. and showing a lamp held therein;

FIG. 4 is a top plan view of the socket of FIG. 1 showing a lamp base held therein (with the lamp envelope removed);

FIGS. 5 and 6 are top plan views of other embodiments of the invention.

Referring to FIGS. 1 through 4, the socket of the present invention includes a hollow husk 10 of a suitable, moldable, plastic insulating material, such as polypropylene plastic. As is known, polypropylene is a mater al which is resilient or semi-resilient, depending upon its thickness, i.e. it has a certain amount of give." The husk 10 is formed with a flared open top 12, adapted to receive a light bulb, and a bottom wall 14. A channel 16 s formed in the bottom of the husk to accommodate a pair of current carrying wires.

Guideways 20 and 22 are formed in opposite sides of the interior wall of the husk to accept and hold by a force fit a respective electrical contact member 24 and 26. The upper portion of contact member 24 protrudes into the husks bulb receiving cavity to engage and make electrical contact with the threaded side 23 of a screwtype lamp base while contact 26 has a right-angle bend to engage the bottom conductive button portion 25 of the bulb base (see FIG. 3).

Each of the electrical contact members 20 and 22 15 formed with a respective prong portion 30 and 32 at its enlarged end held in the guideways 20 and 22 (see FIGS. 2 and 3) to pierce and make contact with the current carrying conductor of a respective one of the wires of a wire-pair 36 which is laid into the socket channel 16. The wires of wire-pair 36 are forced onto the respective prong members of the socket and held in electrical contact therewith by an insert member 38 which has locking tabs 39 for fitting over and holding the insert member to the bottom wall 14 On either side of the channel 16. For a more complete description of the foregoing type of socket, reference is made to copending application of Henry Schick, Ser. No. 493,472, filed Oct. 6, 1965, entitled Lamp Socket and Clip, in the same name of the assignee which issued as Patent No. 3,372,362 on Mar. 5,

Patented Mar. 31, 1970 3 1968. While the present invention is described with respect to a socket of the type shown in the aforesaid application, it should be understood that it has general utility and practicability with any type of a molded electric lamp socket.

In conventional sockets heretofore known, screw threads are usually molded on the interior Walls of the husk 10, so that the base of a lamp bulb can be screwed therein. In the present invention no screw threads are utilized. As shown in FIGS. l-4, a pair of holding members 40 are molded on diametrically opposite sides of the interior wall of the socket substantially from the open top of the husk, or slightly below the top, down to a step 44 also formed on the interior wall of the socket. The usual function of the step 44 is to limit the downward travel of the light bulb as it is fastened into the socket.

Each holding member 40 is preferably integrally formed as part of the husk during the molding thereof and is of the same material as the husk. Each member 40, as shown in FIGS. 14, has a pair of fingers 41 and 42 which branch outwardly, forming an obtuse angle, from a central holding portion 43 located on the internal wall of the husk into the husk cavity. As shown in FIGS. 1 and 2, the upper end of the ribs holding member 40 are generally flared to correspond with the flared open mouth 12 of the socket. The fingers 41 and 42 may be flat or curved slightly in the same general configuration as the bulb base. As shown most clearly in FIG. 1, each of the fingers 41 and 42 projects slightly beyond the interior wall forming the husk cavity, and a recess 46 is formed in the interior wall behind the fingers to permit them to be moved backward into the recess when a bulb is inserted into the socket.

As seen best in FIG. 4, when a lamp bulb is pushed straight down into the socket opening the two fingers 41 and 42 spread apart and are free to move about the central joining point 43 back into the recess 46. Since the fingers 41 and 42 are resilient, or semi-resilient, and can deform, they bend slightly without breaking under the radial force exerted by the bulb. After the bulb is pushed all the way down into the socket, the fingers 41 and 42 tend to return to their normal positions. Because the distance across the husk between the undeformed fingers 41 and 42 of both members 40 is slightly less than the bulb base diameter, and the generally conformed shape of the fingers and the bulb base, the fingers grasp the bulb base and hold it firmly. It should be understood that the fingers 41 and 42 of each member 40 act much in the manner of two gripping fingers, such as the thumb and forefinger, of the human body upon grasping a circular I object. However, the two fingers of each holding member are self-resilient and thereby engage and firmly hold the bulb in the socket.

In FIG. 3, electrical contact member 24 is shown with a projection 50 at its upper end having a size generally equal to the spacing between two crests of the lamp bulb screw thread. The purpose of the projection 50 is twofold. First, it insures better electrical contact between the contact member 24 and the threaded side of the bulb base. Second, it provides an additional force to hold the bulb within the socket since the material of the contact member is of a spring-type material and has a certain amount of resiliency. It should be understood, however, that the projection 50 is not a threaded member since the bulb does not have to be threaded into the socket. Instead, the bulb is pushed vertically down into the socket and, due to its resiliency, the spring-type contact member 24 bends back and its projection 50 snaps into the space between two of the thread crests on the base.

In FIG. 3, the interior wall of the husk is shown as also being formed with another projection 54 of generally curved configuration whose size also corresponds approximately to the size of the valley between two crests of the screw thread of the bulb base. This projection 54 is preferably integrally molded as part of the husk diametrically opposite the contact member projection 50. It has been found that one or more of these wall projections 54 can be spaced around the interior wall of the huskto provide an additional holding member for the bulb to prevent it from popping out of the socket. Each projection 54 need extend for only a small distance, for example about five to twenty degrees around the interior wall circumference.

The projection 50 on the contact member 20 and the one or more additional wall projections 54 provide additional holding force. They are not absolutely necessary, and, it should be understood that the socket of FIGS. 14 can hold the lamp bulb in the socket using only the members 40.

FIG. 5 shows another embodiment of the invention in which a different type of a holding member is utilized. Here, the generally circular husk interior wall is again formed with the two recesses 46 and a generally straight vertical partition 60 is formed in the wall in front of each recess. Each partition 60 is also preferably integrally molded as part of the husk and has a certain amount of resiliency or give. The two partition walls are shown generally parallel to each other. However, it should be understood that this is not essential. Also, three or more such partition walls can be used spaced around the interior wall. If desired, the partitions 60 can also be made slightly curved to better conform to the lamp bulb base. The partition members 60 extend vertically in the husk and are approximately the same height as the holding member of FIGS. 1-4.

In operation of this embodiment of the invention, the lamp is again pushed directly into the socket vertically and the partition members 60 bow outwardly slightly toward and at least partially into the respective recesses 60. This firmly holds the lamp in the socket in the manner previously described by the partitions gripping the bulb base. The projections and 54 may be provided, if desired, although they are not necessary to the proper functioning of the socket.

FIG. 6 shows another embodiment of the invention in which the holding members are formed by two sets of diametrically located ribs. Each set is shown as having three vertical (i.e. parallel to the longitudinal axis of the socket) ribs 62, 64 and 65, for-med on the husk interior wall while the central rib 64 also extends beyond the wall periphery to a lesser extent. When the bulb is pushed into the socket of FIG. 6, the two ,outer ribs 62 and 66 of each set are moved outwardly, away from the center of the husk cavity, and grasp the socket base much as in the manner of the configuration of FIGS. 1-4. The center rib 64 of each n'b set firmly engages the side of the bulb base.

It should be understood that in each of the embodiments described the extent to which a holding member component (fingers 42, 44; partition ribs 62, 64, 66) is made to extend into the husk cavity beyond the periphcry of the interior wall is primarily a function of the minimum tolerance dimension of the bulb to be held in the socket. By making the components long enough to hold the minimum tolerance dimension of a given size bulb, it has been found that the various embodiments of the present invention can accommodate and hold light bulbs of any given size which are within a specified range of dimensional tolerances. This is due to the resiliency of the holding members.

While certain preferred embodiments .of the invention have been described, it is to be understood that the invention may be otherwise embodied.

What is claimed is:

1. A lamp socket for holding a light bulb with a conductive base which is to be pushed therein comprising a one-piece husk .of plastic material formed with a cavity and deformable holding means unitary with the husk and having a portion for engaging a part of the bulb base which holding means portion is spaced from the interior wall portion of the husk cavity, said holding means deforming toward the interior wall portion of the 'husk upon the bulb being inserted into the socket cavity and assuming a position to grip and hold the said part .of the base of a light bulb placed within said cavity after removal of the insertion force, and conductive means held in said husk adapted to make electrical contact with the conductive portion of the bulb base.

2. A lamp socket as set forth in claim 1 wherein said husk is made of polypropylene.

3. A lamp socket as in claim 1 further comprising a projection formed on the electrical contact member to engage the threads of the base of the light bulb.

4. A lamp socket as in claim 1 further comprising a projection formed on the interior wall of the socket to engage the threads of the base of the light bulb.

5. A lampsocket as set forth in claim 1, wherein said husk interior wall is formed with a recess behind at least one of said holding means into which said holding means can move when deformed by a light bulb inserted into the socket.

6. A lamp socket as set forth in claim 5, wherein said holding means comprises a pair of fingers extending from the recess portion of the interior wall and forming an obtuse angle therebetween, the free ends of said fingers adapted for gripping the bulb base, said fingers being of a size to fit within the recess portion when deformed therein.

7. A lamp socket as set forth in claim 5, wherein said holding means comprises a partition wall extending across the cavity and located to have a portion which is deformable into the husk recess when deformed by a light bulb inserted into the socket.

'8. A lamp socket as set forth in claim 5, wherein said holding means comprises a set of spaced ribs at least one of which moves into the recess when deformed by a light bulb inserted into the socket.

9. A lamp socket as set forth in claim 1 wherein said holding means comprises a pair of fingers extending into the husk cavity from the interior wall and located to form an obtuse angle therebetween, the free ends of the fingers for engaging the bulb base.

'10. A lamp socket as in claim 9, wherein two said holding means are provided located diametrically opposite one another.

11. A lamp socket as set forth in claim 1, wherein said holding means comprises a partition wall extending across the cavity.

12. A lamp socket as set forth in claim 11, wherein two said partition walls are provided.

13. A lamp socket as set forth in claim 12, wherein the partition walls are generally parallel to each other.

14. A lamp socket as set forth in claim 1, wherein said holding means comprises a set of spaced ribs extending into said cavity from the husk interior wall.

15. A lamp socket as set forth in claim 14, wherein said set of ribs comprises three ribs, the central rib of the set having a smaller depth than the side ribs.

16. A lamp socket as in claim 1 adapted for lamps with screw type bases wherein said holding means extends generally vertically of said husk and is adapted to engage a plurality of the threads of the bulb base.

17. A lamp socket as in claim 16 wherein said holding means comprises a pair of fingers which extend into the cavity, said fingers moving outwardly toward the husk interior wall upon insertion of a light bulb in a socket each pair of fingers gripping the bulb at two places.

References Cited UNITED STATES PATENTS 2,071,769 2/1937 Sohlicker et al. 339-73 2,647,246 7/1953 Gilbert 339-99 3,101,984 8/1963 Wieckmann 339-69 MARVIN A. CHAMPION, Primary Examiner J. H. MCGLYNN, Assistant Examiner US. Cl. X.R. 33975 

